Smaller Infarct Size with Ticagrelor vs. Clopidogrel in STEMI Patients: Insights from Cardiac MRI

BACKGROUND Ticagrelor has many protective cardiovascular properties in addition to its potent antiplatelet action. This study aims to compare the effects of ticagrelor versus clopidogrel on infarcted mass, quantified by cardiac magnetic resonance imaging (cMRI), in patients with ST-segment elevation acute myocardial infarction (STEMI). METHODS AND RESULTS Adult patients of both sexes with STEMI under pharmaco-invasive strategy were included (n=225). Patients were thrombolized within six hours of symptom onset and underwent angiography and percutaneous coronary interventions, when needed, within the first 24 hours. Before the invasive procedures, patients were randomized to be treated with ticagrelor or clopidogrel (central computerized system). Patients were followed weekly to optimize medical therapy. After 30 days, cMRI was performed and smaller percentage of left ventricular infarcted mass was found with ticagrelor (p=0.012), despite similar angiographic characteristics at baseline (SINTAX score, Gensini score, culprit artery, TIMI flow or myocardial blush). At 30 days, left ventricular ejection fraction (LVEF) was comparable between groups, but the K-means algorithm displayed more homogeneous responses for smaller infarcted mass and better LVEF among those patients treated with ticagrelor. Standard lipid panel and most inflammatory parameters were similar at baseline and after 30 days. However, lower high-sensitivity troponin T and high-sensitivity C-reactive protein levels were found in samples collected from patients treated with ticagrelor, in the first day of STEMI. CONCLUSIONS In patients with STEMI under pharmaco-invasive strategy, therapy with ticagrelor was associated with smaller infarct size than clopidogrel. REGISTRATION URL:https//clinicaltrials.gov; Unique identifier: NCT02428374 . Graphical abstract STEMI-ST-elevation myocardial infarction; OMT- Optimal Medical Treatment; cMRI-cardiac magnetic resonance imaging; hsTNT-high-sensitivity troponin T; hsCRP-high-sensitivity C-reactive protein. CLINICAL PERSPECTIVE What Is New? In patients with STEMI under timely pharmaco-invasive strategy, ticagrelor was associated with smaller infarct size by cMRI at day 30 compared with clopidogrel. This beneficial effect was related to lower serum levels of hsTNT and hsCRP at day 1. Randomized patients had similar pre- and post-reperfusion angiographic characteristics, and received optimal medical therapy. What Are the Clinical Implications? Our findings suggest greater benefit of ticagrelor, possibly related to early cardiomyocyte recovery after reperfusion in STEMI patients. Improvement in microcirculation and attenuation in the inflammatory response may have contributed to the findings. Further studies are needed to investigate the underlying mechanisms and potential clinical implications of these findings.